I have a 1998 V70 X/C awd with 250,000 miles.

According to our mechanic, the oil cooler lines and radiator were leaking. They wanted over $1000 for repair, so I decided to DIY. I removed the radiator and am preparing to remove the oil cooler lines. I bought a new radiator and ordered oil cooler lines and an oil cooler thermostat housing gasket. I called to see about having the oil cooler and transmission cooler tested and they told me to just replace them, do not bother testing them. A replacement oil cooler is another $161 plus shipping and I cannot find a replacement transmission cooler. I also have not replaced the transmission cooler lines and no one seems to sell them. But they were not noticeably leaking.

Should I be replacing all of these things while I have the radiator assembly out of the car? The mechanic did not say they were leaking and I am leery about putting a ton of $ into a car with 250,000 miles on it (although I was told the engine was rebuilt about 40,000 miles ago). It is reaching the point of constant repairs (I already put a heater core in it and a new tailgate latch, and a few other minor items and there are still a handful of items that need attention).

I am not a good mechanic but I can muddle my way through pretty much any repair job eventually. It will probably take me three weekends to get the parts back in once I figure out what all I need. If I can remember where everything goes. I can only work on the car an hour or two each weekend, sometimes not at all, so it takes months to complete a repair. Luckily this is a spare car for winter use.

Oh and what the heck were they thinking with those round nuts that hold the radiator in place? I ended up having to grind the bolts off. Are those round nuts supposed to be fastened in pace somehow? Is there any reason not to replace them with normal nuts and bolts?

Thank you.